Epidermis (skin)

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Cross-section of all skin layers

Epidermis is the outermost layer of the skin. It forms the waterproof, protective wrap over the body's surface and is made up of stratified squamous epithelium with an underlying basal lamina.

[edit] Components

The epidermis is avascular (contains no blood vessels) and is nourished by diffusion from the dermis. The main type or the four principal types of cells which make up the epidermis are keratinocytes, melanocytes, Langerhans cells and Merkels cells. It is a keratinized stratified squamous epithelium.

[edit] Layers

The epidermis is divided into many layers where cells are formed through mitosis at the innermost layers. They move up the strata changing shape and composition as they differentiate and become filled with keratin. They eventually reach the top layer called stratum corneum and become sloughed off, or desquamated. This process is called keratinization and takes place within weeks. The outermost layer of epidermis consists of 25 to 30 layers of dead cells.

[edit] Sublayers

Epidermis is divided into the following 5 sublayers or strata, listed from the superficial to deep:

• Stratum corneum
• Stratum lucidum (not present in thin skin, only thick, hairless skin of palms & soles)
• Stratum granulosum
• Stratum spinosum
• Stratum germinativum (also called "stratum basale")

It is the deepest layer of the skin specifically the epidermis. the anatomical structure of it is composed of a single row of cuboidal of columnar keratinocytes.

Mnemonics used for remembering the layers of the skin (using "stratum basale" instead of "stratum germinativum"):

• "Corn Lovers Grow Several Bales" (from superficial to deep)
• "Come Lets Get Some Beers" (from superficial to deep)
• "Before Signing, Get Legal Counsel" (from deep to superficial)
• Californians Love Girls in String Bikinis C-L-G-S-B(from superficial to deep)

[edit] Additional images

Section of epidermis.	Skinn layer drawing.jpg Skin layers.	Spongiotic dermatitis (2) Dyshidrotic .JPG Histopathological image of dyshidrotic dermatitis, showing focal spongiotic change in the epidermis.	HautAufbau.png Schematics of internal human skin depicting its inner structure.
Gray942.png The distribution of the bloodvessels in the skin of the sole of the foot.	Gray944.png Cross section showing layers of epidermis.

[edit] External links

• Histology at Boston University 08422loa - "Integument: thick skin"

This page uses content from the English-language version of Wikipedia. The original article was at Epidermis (skin). The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.